Gaseous conduction discharge device



Jan 16, 39415. D. E. HENRY GASEOUS CONDUCTION DISCHARGE DEVICE Filed Jan. 16, 1942 INVENTQR a E. f/E/VE. Y

ATTORNEY Patented Jan. 16, 1945 2,367,579 GASEOUS CONDUCTION DISCHARGE EVICE Donald E. Henry, Cedar Grove, N. J., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application January 16, 1942, Serial No. 426,961

6 Claims.

This invention relates to gaseous conduction discharge devices and more particularly to such devices wherein a positive column discharge is maintained between spaced electrodes of the cold cathode type within an elongated tubular envelope, such as for example, in ultra-violet lamps, fluorescent tubes, and the like electrical discharge devices.

One of the objects of the present invention is to provide means to extend the glow discharge between the electrodes over substantially the entire length of the tubular envelope.

Another object is to provide a gaseous conduction discharge device having a relatively low break-down voltage.

Still another object is to increase the extent of glow discharge obtainable in gaseous conduction discharge devices.

Other objects and advantages will be apparent as the invention is more fully hereinafter disclosed.

In accordance with these objects I have found that the glow discharge in gaseous conduction discharge devices having an elongated tubular envelope may be extended over substantially the entire length of the envelope by employing hollow tubular electrodes closed at one end and surfaced interiorly with thermionically active ma-' terial and sustaining the electrodes in substantial axial alignment in spaced relation Within the envelope with the open ends of the electrodes adjacent the ends of the envelope. To lower the break-down voltage therebetween I have found that the closed ends of the electrodes may be provided with extensions extending towards each other a suificient distance to provide the desired space gap therebetween and to still further lower the break-down potential. the ends of said extensions may be surfaced with material of greater thermionic activity than the material comprising the extensions.

Before further disclosing the present invention reference should be made to the accompanying drawing, wherein:

Fig. .l. is a side elevational view of a lamp constructed in accordance with the present inventlon;

Fig. 2 is a section along plane 2-? of Fig. 1;

Fig. 3 is a side elevational view of a modification. of the present invention;

Fig. 4 is a sectional view of the same along plane i-d of Fig. 3;

Fig. 5 is a fragmentary perspective view illusrair-ing one feature of the same; and

Fig. 6 is a side elevational view of another modification.

Referring to the drawing in detail, the device illustrated in Fig. 1 comprises an elongated tubular glass envelope I provided interiorlywith electrodes 2 and 3 in opposite ends thereof, each said electrode being sustained in substantial axial alignment, with the axes of the electrodes and envelope coinciding, by leading-in support wires 4 and 5 respectively, extending through the end walls 9 and In of the envelope i through presses 6 and 1. respectively.

Electrodes 2 and 3 are each comprised of hollow tubular metallic material surfaced interiorly with electron emissive material 3 with the close spaced adjacent electrode ends closed to the passage of an electrical discharge therethrough and the open ends thereof adjacent to and in relatively close spaced relation to the end walls il-i 0 of envelope I. Leading-in support. wires 4-5 of electrodes '2 and 3, preferably extend axially to the closed ends H--l2, substantially as shown,

' and the area of the adjacent spaced ends of electrodes 2 and 3 are preferably of relatively small area as compared to the cross-sectional area of the electrodes, tubstantially as indicated, to provide for a concentration of electrical forces thereon thereby to lower the break-down voltage therebetween in any given gas at any given pressure.

With this arrangement of electrodes 2 and 3, I have found that with any given gas filling within envelope l a relatively low break-down voltage regulated by the precise space gap between the ends H--i2 of electrodes 2 and 3 may be obtained and that any glow discharge obtained between the electrodes 2 and 3 will extend from one tip end (i i) to the open end of the opposite electrode (3). Where the energizing current is alternating current, the glow discharge will alternate back and forth between the open ends of the electrodes 2 and 3 and the closed ends ll-l2 of the opposite electrode. By bringing the open ends of electrodes 2 and 3 in relatively close spaced relation to the end walls 9-30 of envelope l substantially the entire length of the tubular envelope i may be filled with the discharge between electrodes 2 and 3.

As a specific example of this invention; where electrodes 2 and 3 consist of about inch diameter nickel tubing surfaced interiorly with thermionically active alkaline earth metal oxides, with an over-all length of about 1% inches having the ends I l-|2 desirably coated on a small area with electron emission material and spaced apart about 1 millimeter and where the said electrodes are enclosed within a /4 inch tubular glass envelope about 4 inches long, and filled with a mixture of neon (60%) and argon (40%), at a pressure of about 10 millimeters of mercury, and mercury vapor, the lamp will start and operate on 110 volts alternating current with ballast resistance in series therewith.

In the manufacture of the lamp the usual precautions of best modern practice must be followed in order to obtain the desired result.

Referring nowto Fig. 3, where it is desired to provide an envelope I, having a length many times the over-all length of electrodes 2 and 3, the space gap between the closed and facing ends ll--l2 of electrodes 2 and 3 may be bridged by extensions Iii-l4 thereon provided with pointed tip ends l5-l6 in determined spaced relation to each other.

Under substantially the same gas pressure and gas composition given in the first specific embodiment and spacing of tip ends l5l6, the lamp will start and operate on 170 volts alternating current.

The break-down voltage between the electrode ends may be widely varied without essential departure from the present invention by varying the space gap between the adjacent ends ll-I2 or tip ends l5-l6, and by surfacing the ends lI--I2 or tip ends l5|6 with material of lower break-down voltage than the nickel comprising the electrodes 2 and 3, such as for example metallic thorium or other electron emission material, as well as by varying the composition and pressure of the gases enclosed within the envelope, as one skilled in the art will perceive.

Referring now to the embodiment of my invention illustrated in Fig. 6, there is shown a lamp [1 having a pear-shaped bulb l8 and provided with a mount l9 united to the neck portion 2| of said bulb as indicated at 22. Through the press portion 23 of said mount extend relatively thick lead-in conductors 24 and 25, to the inner ends of which are secured hollow cylindrical electrodes 26 and 21 which project at an angle to, or diverge away from, one another as illustrated, so

that their inner or closed ends 28 and 29 are close together, while the outer or open ends are relatively far apart but positioned relatively close to the spherical portion 3! of the envelope l8.

By virtue of the close spacing of the lower or closed ends of the electrodes 26 and 2'! and the lead-in conductors thereto, the breakdown voltage is reduced so that starting is facilitated, the discharge, however, transferring to the open ends of said electrodes because the inner surfaces of the latter are coated with electron emission material like the corresponding electrodes 2 and 3 of the preceding embodiments. If desired the adjacent or closed ends of the electrodes, and/or the closely-spaced portions of the lead-in conductors, may be provided with spots of electron emission material to further facilitate starting, as well as for distributing the discharge between the electrodes after starting, so that said discharge when it becomes steady fllls approximately the entire volume of the envelope, as in the preceding embodiments.

If the distance between the open ends of the electrodes is less than that between the open end of one and the opposite end of the other, then the discharge finally goes between the open ends of said electrodes, as illustrated. If, however, the open end of each electrode is nearer the opposite than the open end of the other electrode, then the discharge alternates, as in the preceding embodiments. between the closed end of one electrode and the open end of the other and viceversa, if alternating current is used.

The present invention is adapted for use, also with either high or low voltage electrical discharge devices, as one skilled in the art will perceive, and with various types of gaseous conduction discharge lamps, such as ultra-violet lamps, fluorescent lamps, wherein a longer discharge path substantially filling the entire length of the tubular envelope is desired.

Having hereinabove described the present invention generically and specifically and given three specific embodiments thereof it is belived apparent that the same may be widely varied without essential departure therefrom and all such modifications and departures are contem' plated as may fall within the scope of the following claims.

I claim:

1. A gaseous conduction discharge device comprising an elongated tubular envelope enclosing a gaseous filling and a pair of bare hollow cylindrical metal electrodes each having one end closed and one and open, thermionically active material on only the inner cylindrical surfaces thereof, and means sustaining the said electrodes with a free space therebetween, in substantial axial alignment, opening outwardly, and disposed closely adjacent the inner surfaces of the ends of the said envelope.

2. The combination of claim 1, wherein means are provided on the closed ends of said electrodes extending axially towards each other so as to leave only a relatively small space therebetween.

3. The combination of claim 1, wherein the closed ends of said electrodes are provided with means extending axially towards each other so as to leave only a relatively small space therebetween, and wherein the ends of said means are surfaced with material of relatively high electron emissivity as compared with the material of said means.

4. A gaseous conduction discharge device comprising an elongated tubular envelope enclosing a gaseous filling and a pair of hollow metal cylindrical electrodes each having its outer surface bare and uncoated, with one end closed and one end open, electron emissive material on the inner surfaces of said electrodes, means sustaining said electrodes in substantially axial alignment spaced from the inner surfaces of said envelope, opening outwardly, and disposed closely adjacent to the inner surfaces of the ends of said envelope. and wires extending from the adjacent closed ends of said electrodes, disposed axially thereof, and with their free ends disposed close to one another in order to provide for easy starting.

, 5. A gaseous conduction discharge device comprising a tubular glass envelope about 4 inches long and inch in diameter and containing inert gas at a pressure of about 10 millimeters of mercury and admixed with mercury vapor, an electrode in each end thereof, each electrode being formed of metal tubing about A inch in dinating current with ballast resistance in series therewith.

6. A gaseous conduction discharge device having an envelope enclosing a gaseous filling and a pair of elongated hollow generally cylindrical metal electrodes, the outer surfaces of which are bare, extending at an acute angle to one another and having their adjacent ends closed and other ends open, the closed ends of said electrodes being provided with means extending toward each other so as to leave only a relatively small space therebetween, the ends of said means being surfaced with material of relatively higher thermionic emissivity than the remainder, thermionically active material on the inner surfaces of said electrodes, and means sustaining said electrodes with their open ends closely adjacent an inner surface of said envelope.

DONALD E. HENRY. 

